The document DE 198 195 43 A1 describes a two-color light-emitting semiconductor device comprising, between its front side and its back side, a first surface-emitting LED (light-emitting diode) having a first active zone that emits radiation in a first wavelength and a second surface-emitting LED having a second active zone that emits radiation in a second wavelength. Disposed between the two active zones is a first reflecting layer that is reflective of the first wavelength and transparent to the second wavelength, and disposed between the second active zone and the back side is a second reflecting layer that is reflective of the second wavelength.
The document U.S. Pat. No. 5,391,896 describes a monolithic, multi-color optoelectronic component comprising an indium phosphite substrate with an upper and a lower side, a first zone that is applied to the surface of the substrate, and a second zone that is applied to the first zone. The first zone is preferably GaInAsP-based and the second zone InP-based. The two zones are grown in lattice-matched fashion. The second zone has a larger band gap than the first zone.
Additional zones having successively increasing band gaps can also be applied. With the component, light of different colors can be emitted and received simultaneously or at different times.